Radiolabeled biomolecules such as peptides and proteins can be used to visualize a variety of diseases through interaction with specific cell surface receptors. Introduction of a molecular entity that allows facile labeling with the medically useful radionuclide Tc-99m without significant alteration of the biopolymer's structure and function is desirable. This proposal focuses on an innovative approach to labeling peptides and proteins with technetium (Tc-99m) and rhenium (Re-188 and Re-186), by creating single amino acid analogs applicable to current peptide synthesis methods that will form a facile and stable complex with Tc-99m. The work outlined here focuses on the development of synthetic strategies and the radiolabeling and testing of Tc-99m-labeled chemotactic peptides containing single amino acid analog chelates, as novel imaging probes for visualizing infection. The objective of the proposal is the design of a family of single amino acid analog chelators based on derivatized lysine and alanine, as well as diamino diacids, for inclusion into synthetic chemotactic peptides via conventional solid phase peptide synthesis (SPPS) methods. The ultimate goal is the formulation of a series of readily available reagents for SPPS that would have broad applicability to both clinical imaging and biomedical research. The approach affords significant flexibility in the choice of donors for 99mTc coordination combined with the considerable advantages afforded by application of routine solid phase synthetic techniques. Importantly, the addition of a chelating moiety as a single amino acid in the peptide sequence should minimize perturbation of structure and function compared to more elaborate chelating groups and provide more readily characterize peptides compared with post synthesis modification using bi-functional chelators. [unreadable] [unreadable]